<p>Irregular wall pulsation is a distinctive feature of certain intracranial aneurysms (IAs) identified by four-dimensional computed tomography angiography (4D-CTA). While clinical studies have demonstrated the association of irregular pulsation with aneurysm instability or rupture, the underlying biomechanical mechanisms remain poorly understood. In this study, we utilized the coherent point drift algorithm combined with elastic theory and computational fluid dynamics to quantify biomechanical parameters of IAs with irregular pulsation based on 4D-CTA images. The methodology was applied to three patient-specific IAs with clinically confirmed irregular pulsation. Obtained results revealed that aneurysm wall regions with irregular pulsation generally displayed large wall displacement, which was either accompanied or not accompanied by high strain. Notably, large displacement or high strain could also be detected in some aneurysm wall regions without irregular pulsation, as well as in adjacent normal arteries. Hemodynamic simulations demonstrated the presence of low and oscillatory wall shear stress (WSS) in irregular pulsation regions. Comparisons between dynamic hemodynamic models (incorporating wall movement) and static hemodynamic models (with rigid walls) further revealed the role of irregular pulsation in amplifying WSS oscillation, which implies that the degradation of wall mechanics in aneurysm regions with irregular pulsation may interact with hemodynamic disturbance in a mutually reinforcing manner. In summary, the findings of our study suggest that quantifying biomechanical parameters in both the wall and sac of aneurysm may provide valuable insights for assessing the risk of IAs, particularly those exhibiting irregular pulsation.</p>